completing the square: Meaning and Definition of

complet'ing the square'

1. a method, usually of solving quadratic equations, by which a quadratic expression, as x − 4x + 3, is written as the sum or difference of a perfect square and a constant, x − 4x + 4 + 3 − 4 = (x − 2) − 1, by addition and subtraction of appropriate constant terms.